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High · 8.2 CVE-2026-92698 EUVD-2026-117874

FastNetMon: sFlow header_size field trusted as parser capture length causes remote out-of-bounds read

Published Nov 5, 2026 · Updated Nov 9, 2026 · Assigned by GitHub_M

Description

FastNetMon is a high-performance DDoS detector and sensor. In version 1.2.9 and earlier, process_sflow_flow_sample() in src/sflow_plugin/sflow_collector.cpp passes the attacker-controlled sflow_raw_protocol_header_t.header_size to parse_raw_packet_to_simple_packet_full() as its trusted captured length without comparing it with the bytes remaining in the record. An inflated header_size creates a false end pointer beyond the received sFlow v5 UDP buffer, defeating the nested parser's bounds checks and causing an unauthenticated remote out-of-bounds read and process crash, with possible limited exposure of adjacent bytes through parsed flow fields. No fixed release is available as of this review.

Affected products

VendorProductAffectedFixed
pavel-odintsov fastnetmon <= 1.2.9 —

Fixed in Linux distributions

Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.

ReleasePackageFixed inAdvisory
Debian 14 fastnetmon No fix yet —
Debian 13 fastnetmon No fix yet —
Debian 12 fastnetmon No fix yet —
ReleasePackageFixed inAdvisory
Ubuntu 26.10 fastnetmon No fix yet —
Ubuntu 18.04 LTS fastnetmon No fix yet —
Show 3 more (older releases, extended support, other products)
ReleasePackageFixed inAdvisory
Ubuntu Pro 26.04 LTS fastnetmon No fix yet —
Ubuntu Pro 24.04 LTS fastnetmon No fix yet —
Ubuntu Pro 20.04 LTS fastnetmon No fix yet —

References